The Tamarack® Vista® applicator is a commercial product used to feed, cut, and apply paper and thin film materials to folding cartons. The Vista applicator applies window patches over a die cut opening in a folding carton, and it may also apply labels, microwave susceptor patches, RFID inlays, release liner, reinforcing patches and other materials onto folding cartons, sheets of paper, or corrugated paperboard. The Tamarack Vista is disclosed in U.S. Pat. No. 6,772,663 particularly in relation to FIGS. 4, 5A and 5B; in U.S. Pat. No. 7,901,533 particularly in relation to FIGS. 10 and 11; and in U.S. patent application Ser. No. 12/751,014 particularly in relation to FIG. 1. The disclosures in the aforementioned published documents are hereby incorporated by reference in the present application in their entirety.
The Vista applicator utilizes a blade or blades mounted in a rotary cutting cylinder. The material to be cut is pinched between the blade tip and an anvil strip which rides atop a vacuum belt, or belts. The anvil surface is typically a thin, hardened, flat steel surface. As the cutting blade contacts the essentially stationary anvil strip, the blade pushes the anvil strip slightly ‘downwards’, i.e., away from the blade, into contact with a typically moving belt surface, and the resulting friction force between the moving belt and the anvil strip accelerates the anvil strip. The tangential component of the motion of the blade tip contacting the anvil strip also accelerates the anvil strip. After the material to be cut is severed between the blade tip and the anvil strip, the blade tip, following the cutting blade's rotary path, breaks contact with the anvil strip. The anvil strip is then propelled back towards its initial position by a spring force provided by coil springs. Every cutting cycle thereby imparts a cyclic, reciprocating motion to the anvil strip.
In prior art Vista® applicators, the anvil strip rode atop a portion of the vacuum belts where the belts traveled in a straight path. The anvil strip was guided in this straight path by steel rods. In a subsequent version of the Vista applicator, the vacuum belt section was redesigned to provide two separate belt sections. The upper, or infeeding, belt section was driven by its own servo motor and programmed to provide stop-and-go infeeding, just as the feed cylinder provided stop-and-go feeding of the film. This change allowed a reduction in the infeeding tension on the material to be cut which was beneficial for accurately feeding ‘stretchy’ materials (those with a relatively low modulus of elasticity) such as polyethylene and latex rubber. The lower, or outfeeding, belt section was driven by its own servo motor at an essentially constant speed that followed the conveyor or carrier belt speed of the host carton folder/gluer machine. The outfeeding belt section then conveyed the cut piece of film to be joined onto a carton blank, or the like.
With two belt sections, there resulted a ‘gap’ between the two sections. In order to minimize the ‘gap’ between upper and lower belt sections that the film was fed through, it was desirable to locate the anvil strip over a curved portion of the lower, or outfeeding, belt path. It thereby became desirable to provide a curved reciprocating path for anvil strip transit. The anvil strip itself was also shaped into a curve relative to its end view section to comply with the curved portion of the belt path.
Other changes to the lower belt section reduced space between the belts. As the belts support the anvil strip, the reduced space between the belts allowed for the use of a thinner anvil strip, while still providing sufficient rigidity to effectively resist the cutting forces. A thinner anvil strip also reduces reciprocating forces allowing the use of lighter springs and guides. Reduced reciprocating forces also reduces wear on the blade tip and potentially allows for higher process speeds.
Occasionally, the cutting process may be interrupted by: (1) a jam-up, i.e., material may undesirably accumulate in the cutting area due to the lead edge of the material getting caught or obstructed; (2) a blade failing to complete a cut; or (3) adhesive buildup on moving parts causing the film to stick, or other mechanical failures. The anvil strip was provided with intentionally weakened mounting parts to allow the anvil strip to break-away in the event of a jam-up. However, these parts could still be damaged in a jam-up.